Processing state detecting device, laser processing machine, and machine learning device

ABSTRACT

A processing state detecting device for detecting a processing state of a workpiece processed by laser processing includes: a sound collecting unit that measures sound while the workpiece is being processed by laser processing; an installation position evaluating unit that determines whether an installation position of the sound collecting unit needs to be changed, on the basis of the sound measured by the sound collecting unit; and an evaluation result informing unit that provides information on a result of evaluation of the installation position evaluating unit.

FIELD

The present invention relates to a processing state detecting devicethat detects a processing state of a workpiece in laser processing, alaser processing machine, and a machine learning device.

BACKGROUND

A method of using sound produced during processing to detect aprocessing state of a workpiece has been proposed as a technique fordetecting a processing state of a workpiece in laser processing.

In an inventive technique described in Patent Literature 1, it isdetermined that laser ablation starts to occur when a change in anacoustic wave output obtained by measuring sound (acoustic wave)produced during laser processing of a workpiece using an acoustic sensoris detected.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Application Laid-open No. H08-90261

SUMMARY Technical Problem

In order to achieve accurate detection in measuring sound producedduring the laser processing to detect a processing state, theinstallation position of an acoustic sensor is highly significant. Forexample, in a case where the installation position of an acoustic sensoris close to a processing point, assist gas emitted from a nozzle of aprocessing head may be directly sprayed on the acoustic sensor. In thiscase, since a measurement signal outputted by the acoustic sensorcontains wind noise produced by an assist gas being sprayed onto theacoustic sensor, it is difficult to accurately detect a processingstate. In contrast, when the position of the acoustic sensor is too farfrom the processing point, the volume of processing sound to be measuredis insufficient, and a sufficient signal-to-noise ratio (SNR) cannot beobtained. In this case as well, it is difficult to accurately detect aprocessing state.

Thus, in order to accurately detect a processing state, an acousticsensor needs to be installed at a position where an appropriate balancebetween the amount of wind noise contained in a measurement signal andthe volume of the processing sound can be achieved, but in practice, thevolume of processing sound and the gas pressure of the assist gas varydepending on the material of a workpiece. In other words, an appropriateposition of an acoustic sensor differs depending on the material of aworkpiece. As described above, Patent Literature 1 describes that aprocessing state is determined on the basis of processing sound(acoustic wave output) obtained by measuring sound produced during laserprocessing using an acoustic sensor. According to the inventivetechnique described in Patent Literature 1, however, because theinstallation position of the acoustic sensor is fixed, a change in thematerial of a workpiece may get off the balance between the amount ofwind noise contained in a measurement signal and the volume ofprocessing sound, thereby possibly leading to deterioration in detectionaccuracy.

The present invention has been made in view of the above circumstances,and an object thereof is to provide a processing state detecting devicecapable of improving the accuracy of detection of a processing state.

Solution to Problem

In order to solve the above-mentioned problems and achieve the object,the present invention provides a processing state detecting device fordetecting a processing state of a workpiece processed by laserprocessing, the processing state detecting device comprising: a soundcollecting unit to measure sound while the workpiece is being processedby laser processing; an installation position evaluating unit todetermine whether an installation position of the sound collecting unitneeds to be changed, on the basis of the sound measured by the soundcollecting unit; and an evaluation result informing unit to provideinformation on a result of evaluation of the installation positionevaluating unit.

Advantageous Effects of Invention

A processing state detecting device according to the present inventionproduces an advantageous effect that the accuracy of detection of aprocessing state can be improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an example of a configuration of alaser processing machine including a processing state detecting deviceaccording to a first embodiment.

FIG. 2 is a diagram illustrating an example of a configuration of theprocessing state detecting device according to the first embodiment.

FIG. 3 is a chart for explaining a result of learning performed by alearning unit.

FIG. 4 is a flowchart illustrating an example of an operation of theprocessing state detecting device according to the first embodiment.

FIG. 5 is a diagram illustrating an example of a configuration of alaser processing machine including a processing state detecting deviceaccording to a second embodiment.

FIG. 6 is a diagram illustrating an example of a configuration of theprocessing state detecting device according to the second embodiment.

FIG. 7 is a flowchart illustrating an example of an operation of theprocessing state detecting device according to the second embodiment.

FIG. 8 is a diagram illustrating an example of a configuration of aprocessing state detecting device according to a third embodiment.

FIG. 9 is a diagram illustrating an example of a configuration ofhardware by which the processing state detecting devices according tothe first to third embodiments are implemented.

DESCRIPTION OF EMBODIMENTS

A processing state detecting device, a laser processing machine, and amachine learning device according to exemplary embodiments of thepresent invention will be described in detail below with reference tothe drawings. Note that the present invention is not necessarily limitedby these embodiments.

First Embodiment

FIG. 1 is a diagram illustrating an example of a configuration of alaser processing machine including a processing state detecting deviceaccording to a first embodiment. A laser processing machine 100according to the first embodiment includes a processing state detectingdevice 1, a processing machine control unit 21, a processing head 22,and a nozzle 23, and processes a workpiece 30 by irradiating theworkpiece 30 with laser light. The processing state detecting device 1includes a sound collecting unit 11 that measures sound, and adetermination processing unit 10 that determines whether or not laserprocessing is performed normally by the laser processing machine 100 andwhether or not the position at which the sound collecting unit 11 isinstalled is appropriate on the basis of a measurement signal outputtedfrom the sound collecting unit 11. The processing state detecting device1 is a device configured to detect a processing state when the laserprocessing machine 100 subjects the workpiece 30 to laser processing.Although not illustrated in FIG. 1, the processing state detectingdevice 1 further includes a data acquisition unit and a learning unit,which will be described later.

The processing machine control unit 21 performs control for laserprocessing of a workpiece 30, to make adjustment of the position of theprocessing head 22, irradiation of the workpiece 30 with laser light,emission of assist gas, and the like. The processing head 22 has aleading end to which the nozzle 23 is attached, and applies laser lightemitted from a laser oscillator, which is not illustrated, through thenozzle 23 toward the workpiece 30. At the same time, the processing head22 emits assist gas supplied from an assist gas supplying unit, which isnot illustrated, to the outside from the nozzle 23.

FIG. 2 is a diagram illustrating an example of a configuration of theprocessing state detecting device according to the first embodiment. Theprocessing state detecting device 1 according to the first embodimentincludes the sound collecting unit 11, an analog to digital (AD)conversion unit 12, an installation position evaluating unit 13, anevaluation result informing unit 14, a processing state detecting unit15, a processing state informing unit 16, a data acquisition unit 17,and a learning unit 18. The AD conversion unit 12, the installationposition evaluating unit 13, the evaluation result informing unit 14,the processing state detecting unit 15, and the processing stateinforming unit 16 constitute the determination processing unit 10. Inaddition, the data acquisition unit 17 and the learning unit 18constitute the machine learning device 40.

The sound collecting unit 11 is an acoustic sensor such as a microphone,which is provided inside the processing head 22 of the laser processingmachine 100, for example. The sound collecting unit 11 measures sound,that is, collects sound, and generates and outputs a measurement signalrepresenting the collected sound. The sound collected by the soundcollecting unit 11 includes processing sound and noise, the processingsound corresponding to sound produced by laser processing of a workpiece30 performed by the laser processing machine 100. In this specification,some components of the sound collected by the sound collecting unit 11,obtained by subtracting a component of the processing sound from thecollected sound are assumed to be noise components. Note that theposition at which the sound collecting unit 11 is installed is notlimited to the inside of the processing head 22. It may be installedoutside the processing head 22 or may be installed at some portion orcomponent other than the processing head. The sound collecting unit 11may be installed at any position where the sound collecting unit 11 canmeasure the processing sound.

The AD conversion unit 12 converts the measurement signal outputted fromthe sound collecting unit 11 into a digital signal, and outputs ameasurement signal in digital form. To avoid complication ofexplanation, a measurement signal in digital form outputted from the ADconversion unit 12 may simply be referred to as a “measurement signal”in the following description. Note that it is allowable that theprocessing performed by the AD conversion unit 12 is alternativelyperformed by the sound collecting unit 11. Specifically, a configurationin which the AD conversion unit 12 is removed and the sound collectingunit 11 outputs a measurement signal in digital form may be used.

The installation position evaluating unit 13 determines whether or notthe installation position of the sound collecting unit 11 is appropriateon the basis of the measurement signal outputted from the AD conversionunit 12.

The evaluation result informing unit 14 informs the user of theprocessing state detecting device 1 of an evaluation result from theinstallation position evaluating unit 13.

The processing state detecting unit 15 detects a processing state of aworkpiece 30 subjected to laser processing performed by the laserprocessing machine 100, that is, whether or not the laser processing onthe workpiece 30 is being normally performed, on the basis of themeasurement signal outputted from the AD conversion unit 12.

The processing state informing unit 16 informs the user of theprocessing state detecting device 1 of a detection result of theprocessing state from the processing state detecting unit 15.

The data acquisition unit 17 acquires learning data to be used by thelearning unit 18 for generating a learning model, described later, fromthe outside of the processing state detecting device 1.

The learning unit 18 performs machine learning with use of the learningdata received from the data acquisition unit 17, and generates alearning model to be used by the processing state detecting unit 15 todetect a processing state of a workpiece 30. The learning unit 18generates the learning model before the processing state detecting unit15 starts a process of detecting a processing state of a workpiece 30.

The learning data acquired by the data acquisition unit 17 includemeasured sound data and data on a processing state, the measured sounddata being obtained by digitalizing sound collected while the laserprocessing machine 100 from which the processing state detecting device1 is to detect a processing state performs laser processing on theworkpiece 30 to form corresponding data. The data on the processingstate included in the learning data is data indicating a processingresult, that is, whether or not the laser processing has been performednormally, and serves as teacher data for the machine learning. Thedetermination on whether or not the laser processing has been performednormally is made by an operator who uses the laser processing machine100 visually checking a processed product that is the workpiece 30 aftercompletion of the laser processing. The collection of sound while thelaser processing machine 100 performs laser processing of the workpiece30 is assumed to have been performed by a device (acoustic sensor)similar to the sound collecting unit 11. In addition, the device thatcollects sound is assumed to be installed at an appropriate position ofthe processing head 22. The measured sound data is data in the same formas the measurement signal outputted by the AD conversion unit 12 of theprocessing state detecting device 1. The number of sets of such learningdata acquired by the data acquisition unit 17 corresponds to the numberthereof necessary for the learning unit 18 to generate a learning model.Although no specific number is defined, it is desirable that the numberof learning data sets generated when the laser processing has beennormally performed be about the same as the number of learning data setsgenerated when the laser processing has not been normally performed andthe number be as large as possible. As the number of learning data setsacquired by the data acquisition unit 17 is larger, the accuracy of thelearning model generated by the learning unit 18 increases, therebyresulting in improvement of the accuracy of detecting a processing statein the processing state detecting unit 15, that is, the accuracy ofdetermination on whether or not a processing state is satisfactory.

Upon receiving the learning data from the data acquisition unit 17, thelearning unit 18 analyzes the measured sound data and extracts a featurequantity therefrom. The learning unit 18 extracts the feature quantityby performing FFT (fast Fourier transform) on the measured sound datafor each predetermined period to obtain a spectrum and performing filterbank analysis on the obtained spectrum, for example. The learning unit18 may perform spectrum analysis instead of the filter bank analysis.Subsequently, the learning unit 18 stores the extracted feature quantityin association with data on the processing state included in thelearning data. If two kinds of feature quantities are to be extractedfrom the measured sound data by the learning unit 18, coordinates givenby feature vectors having the two kinds of feature quantities aselements have a distribution as illustrated in FIG. 3.

FIG. 3 is a chart for explaining a result of learning performed by thelearning unit 18. FIG. 3 illustrates an example of the distribution ofthe coordinates given by the feature vectors having the featurequantities extracted by the measured sound data as elements. Inaddition, in FIG. 3, a white circle (○) represents a coordinatecorresponding to the feature quantity obtained from the measured sounddata when the laser processing has been performed normally, and a blackcircle (●) represents a coordinate corresponding to the feature quantityobtained from the measured sound data when the laser processing has beenperformed abnormally. Note that, for simplicity of explanation, FIG. 3illustrates a learning result when two kinds of feature quantities areused for the learning performed by the learning unit 18. When thelearning of the measured sound data is advanced and a sufficient numberof feature quantities are obtained, the learning unit 18 obtains aboundary 201 between a first range that is a distribution range ofcoordinates corresponding to the feature vectors having, as elements,the feature quantities obtained from the measured sound data when thelaser processing has been performed normally, and a second range that isa distribution range of coordinates corresponding to the feature vectorshaving, as elements, the feature quantities obtained from the measuredsound data when the laser processing has been performed abnormally.While the case where the number of kinds of feature quantities is two isillustrated in FIG. 3, a boundary is obtained similarly also in a casewhere the number of kinds of feature quantities is three or larger.Specifically, even when three or more kinds of feature quantities arelearned, a certain boundary is present between a first range in whichthe coordinates corresponding to the feature vectors having, aselements, the feature quantities obtained from the measured sound datawhen the laser processing has been performed normally are distributedand a second range in which the coordinates corresponding to the featurevectors having, as elements, the feature quantities obtained from themeasured sound data when the laser processing has been performedabnormally are distributed. The learning unit 18 uses a mixture normaldistribution model, which is also called a Gaussian mixture model (GMM),for example, to determine the boundary 201 between the first range andthe second range mentioned above. The learning unit 18 may use atechnique such as a support vector machine (SVM), a neural network, deepleaning, or linear discriminant analysis (LDA) to determine the boundary201 between the first range and the second range mentioned above.

Upon completing generation of a learning model, the learning unit 18outputs the generated learning model to the processing state detectingunit 15.

While it has been described that the processing state detecting device 1includes the learning unit 18 and the learning model to be used by theprocessing state detecting unit 15 is generated inside the processingstate detecting device 1, the learning model may be generated by somedevice external to the processing state detecting device 1. In thiscase, the data acquisition unit 17 acquires the learning model generatedby the external device and passes the learning model to the processingstate detecting unit 15.

Upon receiving a measurement signal from the AD conversion unit 12 in astate in which the processing state detecting unit 15 holds a learningmodel generated by the learning unit 18, the processing state detectingunit 15 analyzes the measurement signal and extracts a feature quantitytherefrom. The process of extracting a feature quantity from ameasurement signal performed by the processing state detecting unit 15is similar to the process of extracting a feature quantity from measuredsound data in a learning operation when the learning unit 18 generates alearning model. The processing state detecting unit 15 compares theextracted feature quantity with the learning model generated by thelearning unit 18 to determine whether or not the laser processing whenthe measurement signal received from the AD conversion unit 12 isobtained has been performed normally. Specifically, the processing statedetecting unit 15 determines whether or not a coordinate obtained fromeach extracted feature quantity is within the distribution range ofcoordinates obtained from feature quantities obtained when the laserprocessing has been performed normally. The processing state detectingunit 15 outputs, to the processing state informing unit 16, thedetection result of the processing state indicating whether or not thelaser processing has been performed normally.

The processing state informing unit 16 informs the user of the detectionresult received from the processing state detecting unit 15. Theprocessing state informing unit 16 provides the information on theprocessing state by means of displaying on a display unit, sounding of abuzzer, lighting of a lamp, which are not illustrated, or something likethat. The processing state informing unit 16 may provide informationwhen an abnormal processing state is detected by the processing statedetecting unit 15, but not provide information when the processing stateis normal. Alternatively, the processing state informing unit 16 mayinform the processing machine control unit 21 illustrated in FIG. 1 ofan abnormal processing state in addition to the process of informing theuser of the abnormal processing state. In this case, upon receiving theinformation on the abnormal processing state, the processing machinecontrol unit 21 performs such control as automatically stopping themachine processing, or automatically changing a processing parameter toavoid occurrence of a processing fault, for example. Examples of theprocessing parameter to be changed include an output of the laser, andthe height of the processing head 22.

Next, the operation in which the processing state detecting device 1according to the first embodiment evaluates whether or not theinstallation position of the sound collecting unit 11 is appropriatewill be explained. FIG. 4 is a flowchart illustrating an example of theoperation of the processing state detecting device 1 according to thefirst embodiment. The flowchart given in FIG. 4 illustrates theoperation of the processing state detecting device 1 evaluating theinstallation position of the sound collecting unit 11. The processingstate detecting device 1 starts the operation according to the flowchartof FIG. 4 at the same time as the timing when the laser processingmachine 100 starts machine processing of the workpiece 30 or adetermined time before the timing when the laser processing machine 100starts the processing.

The processing state detecting device 1 initially measures soundproduced when the laser processing machine 100 processes the workpiece30 (step S11). Specifically, the sound collecting unit 11 measuressound, and outputs a measurement signal indicating the measurementresult. Subsequently, the processing state detecting device 1 analyzesthe measured sound (step S12). In this step S12, the AD conversion unit12 first converts the measurement signal outputted from the soundcollecting unit 11 into a digital signal, and the installation positionevaluating unit 13 analyzes a measurement signal in digital form.Specifically, the installation position evaluating unit 13 obtainsprocessing sound and noise components other than the processing soundincluded in the measurement signal. The noise components include a windnoise component. Note that the installation position evaluating unit 13is assumed to hold information on the frequency band of the processingsound. The information on the frequency band of the processing sound isgenerated by means of a process according to such a manner that thesound collecting unit 11 measures sound in each of a state in which thelaser processing machine 100 is not performing laser processing and astate in which the laser processing machine 100 is performing laserprocessing, and the installation position evaluating unit 13 analyzestwo measurement signals in digital form indicating the measurementresults, for example. Specifically, frequency spectra of the twomeasurement signals are firstly obtained, the two frequency spectra aresubsequently compared with each other, and then information on thefrequency band of the processing sound is generated. The process ofgenerating the information on the frequency band of the processing soundis performed before the processing state detecting device 1 starts theoperation of evaluating whether or not the installation position of thesound collecting unit 11 is appropriate.

Subsequently, the processing state detecting device 1 determines whetheror not the installation position of the sound collecting unit 11 isappropriate on the basis of the analysis result in step S12 (step S13).The determination in this step S13 is performed by the installationposition evaluating unit 13. The installation position evaluating unit13 determines that the installation position of the sound collectingunit 11 is appropriate if the SNR of the processing sound has a level atwhich the processing state detecting unit 15 can accurately determinethe processing state of the workpiece 30. The installation positionevaluating unit 13 determines that the processing state detecting unit15 can accurately determine the processing state of the workpiece 30 ifthe SNR of the processing sound is larger than a first threshold that ispredetermined, for example. The first threshold to be used by theinstallation position evaluating unit 13 for the determination processin step S13 is beforehand determined through simulation or the like.

If the installation position of the sound collecting unit 11 isappropriate (step S13: Yes), the processing state detecting device 1terminates the operation illustrated in FIG. 4. If the installationposition of the sound collecting unit 11 is not appropriate (step S13:No), the processing state detecting device 1 determines whether or notthe processing sound is small (step S14). Specifically, the installationposition evaluating unit 13 determines whether or not the intensity ofthe processing sound obtained in step S12 is lower than a secondthreshold that is predetermined. Note that the second threshold used inthe determination process in step S14 is different from the firstthreshold used in the determination process in step S13 described above.The second threshold to be used in the determination process in step S14is beforehand determined through simulation or the like.

If the processing sound is small (step S14: Yes), the processing statedetecting device 1 informs the user that the installation position ofthe sound collecting unit 11 should be closer to the workpiece 30 (stepS16). The informing in this step S16 is performed by the evaluationresult informing unit 14. The evaluation result informing unit 14informs the user that the installation position of the sound collectingunit 11 needs to be closer to the workpiece 30 by means of causing adisplay device to display the same, or some means like that. Theevaluation result informing unit 14 may inform the user by sounding of abuzzer, lighting of a lamp, or the like. After performing step S16, theprocessing state detecting device 1 terminates the operation illustratedin FIG. 4.

If the processing sound is large, that is, if the intensity of theprocessing sound is equal to or higher than a third threshold that ispredetermined (step S14: No), the processing state detecting device 1determines whether or not the noise is large (step S15). Specifically,the installation position evaluating unit 13 determines whether or notthe intensity of the noise components obtained in step S12 is higherthan the third threshold. Note that the third threshold used in thedetermination process in step S15 is different from the first thresholdused in the determination process in step S13 described above and thesecond threshold used in the determination process in step S14 describedabove. The third threshold to be used in the determination process instep S15 is beforehand determined through simulation or the like.

If the noise has a low level, that is, if the intensity of the noisecomponents is lower than a predetermined intensity (step S15: No), theprocessing state detecting device 1 terminates the operation illustratedin FIG. 4. If the noise is large (step S15: Yes), the processing statedetecting device 1 informs the user that the installation position ofthe sound collecting unit 11 should be moved away from the workpiece 30(step S17). The informing in this step S17 is performed by theevaluation result informing unit 14. The evaluation result informingunit 14 informs the user that the installation position of the soundcollecting unit 11 needs to be moved away from the workpiece 30 by meansof displaying the same on a display device, or some means like that. Theevaluation result informing unit 14 may inform the user by sounding of abuzzer, lighting of a lamp, or the like. After performing step S17, theprocessing state detecting device 1 terminates the operation illustratedin FIG. 4.

As described above, in the processing state detecting device 1, thesound collecting unit 11 measures sound produced when the laserprocessing machine 100 machine-processes a workpiece 30. Theinstallation position evaluating unit 13 determines whether or not theinstallation position of the sound collecting unit 11 is appropriate,that is, whether the installation position of the sound collecting unit11 needs to be changed, on the basis of a measurement signal indicatinga measurement result of the sound from the sound collecting unit 11. Ifthe installation position of the sound collecting unit 11 needs to bechanged, the installation position evaluating unit 13 then determineshow the installation position of the sound collecting unit 11 should bechanged, on the basis of the intensities of the processing sound and thenoise components included in the sound measured by the sound collectingunit 11. The evaluation result informing unit 14 informs the user of theevaluation result from the installation position evaluating unit 13,that is, more specifically, how the installation position of the soundcollecting unit 11 should be changed. By so doing, the user of theprocessing state detecting device 1 can change the installation positionof the sound collecting unit 11 to an appropriate position. Thus, whenthe installation position of the sound collecting unit 11 is deviatedfrom an appropriate position for a reason of a change in the material ofthe workpiece 30, and/or some other reason, the processing statedetecting device 1 can inform the user of necessity to change theinstallation position of the sound collecting unit 11 to an appropriateposition, so that the installation position of the sound collecting unit11 actually comes to the appropriate position. Thus, the processingstate detecting device 1 can detect the processing states of workpieces30 made of various materials with high accuracy, thereby improving theaccuracy of detection of the processing state.

While it has been described that, when the installation position of thesound collecting unit 11 is determined not to be appropriate, theprocessing state detecting device 1 determines how the sound collectingunit 11 should be changed and informs the user of the same, thisinforming is not essential. The processing state detecting device 1 onlyhas to inform the user at least that the installation position of thesound collecting unit 11 is not appropriate. When the user is informedthat the installation position of the sound collecting unit 11 is notappropriate, the user is expected to change the installation position ofthe sound collecting unit 11. A change in the installation positionimproves the accuracy of detecting the processing state in theprocessing state detecting device 1.

Second Embodiment

FIG. 5 is a diagram illustrating an example of a configuration of alaser processing machine including a processing state detecting deviceaccording to a second embodiment. A laser processing machine 100 aaccording to the second embodiment includes a processing state detectingdevice 1 a, the processing machine control unit 21, the processing head22, and the nozzle 23. Specifically, the laser processing machine 100 ahas a configuration obtained by replacing the processing state detectingdevice 1 included in the laser processing machine 100 according to thefirst embodiment by the processing state detecting device 1 a. Theconfiguration of the laser processing machine 100 a other than theprocessing state detecting device 1 a is common to that in the firstembodiment, and so the description of the components common to those inthe first embodiment will not be repeated. The processing statedetecting device 1 a includes a plurality of sound collecting units 11₁, 11 ₂, and 11 ₃ provided in the processing head 22, and adetermination processing unit 10 a. Although not illustrated in FIG. 5,the processing state detecting device 1 a further includes a dataacquisition unit 17 and a learning unit 18 in a manner similar to theprocessing state detecting device 1 according to the first embodiment.While an example in which the processing state detecting device 1 aincludes three sound collecting units 11 ₁, 11 ₂, and 11 ₃ isillustrated in FIG. 5, the number of sound collecting units included inthe processing state detecting device 1 a may be two or may be four ormore.

FIG. 6 is a diagram illustrating an example of a configuration of aprocessing state detecting device 1 a according to the secondembodiment. The processing state detecting device 1 a includes two ormore sound collecting units 11 ₁, 11 ₂, 11 ₃, . . . , two or more ADconversion units 12 ₁, 12 ₂, 12 ₃, . . . , an installation positionevaluating unit 13 a, the processing state detecting unit 15, theprocessing state informing unit 16, the data acquisition unit 17, thelearning unit 18, and a data selecting unit 19. The AD conversion units12 ₁, 12 ₂, 12 ₃, . . . , the installation position evaluating unit 13a, the processing state detecting unit 15, and the processing stateinforming unit 16 constitute the determination processing unit 10 a.

In the processing state detecting device 1 a, the processing statedetecting unit 15, the processing state informing unit 16, the dataacquisition unit 17, and the learning unit 18 are the same as theprocessing state detecting unit 15, the processing state informing unit16, the data acquisition unit 17, and the learning unit 18 of theprocessing state detecting device 1 according to the first embodiment,respectively. The description of the processing performed by thesecomponents will not be repeated.

In the processing state detecting device 1 a, the two or more soundcollecting units 11 ₁, 11 ₂, 11 ₃, . . . are installed at differentpositions inside the processing head 22 of the laser processing machine100 a. Note that each of the sound collecting units 11 ₁, 11 ₂, 11 ₃, .. . is the same as the sound collecting unit 11 of the processing statedetecting device 1 according to the first embodiment. Thus, thedescription of the processing performed by the sound collecting units 11₁, 11 ₂, 11 ₃, . . . will not be repeated. In the following description,the sound collecting units 11 ₁, 11 ₂, 11 ₃, . . . may be referred tocollectively as sound collecting units 11, each sound collecting unit11, or some other wording.

In addition, each of the AD conversion units 12 ₁, 12 ₂, 12 ₃, . . . ofthe processing state detecting device 1 a is the same as the ADconversion unit 12 of the processing state detecting device 1 accordingto the first embodiment. Thus, the description of the processingperformed by the AD conversion units 12 ₁, 12 ₂, 12 ₃, . . . will not berepeated. Note that, in the following description, the AD conversionunits 12 ₁, 12 ₂, ¹² ₃, . . . may be referred to collectively as ADconversion units 12, each AD conversion unit 12, or some other wording.

In the processing state detecting device 1 a, a measurement signal indigital form, outputted from each of the AD conversion units 12 isinputted to the installation position evaluating unit 13 a and the dataselecting unit 19.

The installation position evaluating unit 13 a compares the qualities ofthe measurement signals inputted from the AD conversion units 12, anddetermines the measurement signal to be used by the processing statedetecting unit 15 for the process of detecting the processing state ofthe workpiece 30. The installation position evaluating unit 13 adetermines a measurement signal with the best SNR, for example, amongthe inputted measurement signals as a signal to be used for the processof detecting the processing state of the workpiece 30 by the processingstate detecting unit 15. The installation position evaluating unit 13 anotifies the data selecting unit 19 of the result of determination.

The data selecting unit 19 selects a measurement signal indicated by thedetermination result of which the data selecting unit 19 is notified bythe installation position evaluating unit 13 a, from among themeasurement signals inputted from the AD conversion units 12, andoutputs the selected measurement signal to the processing statedetecting unit 15.

FIG. 7 is a flowchart illustrating an example of an operation of theprocessing state detecting device 1 a according to the secondembodiment. The flowchart of FIG. 7 illustrates the operation ofdetermining a measurement signal to be used by the processing statedetecting unit 15 in the process of detecting the processing state ofthe workpiece 30. The processing state detecting device 1 a starts theoperation according to the flowchart of FIG. 7 at the same time as thetiming when the laser processing machine 100 a starts machine processingof the workpiece 30 or a determined time before the timing when thelaser processing machine 100 starts the processing.

In the processing state detecting device 1 a, each sound collecting unit11 initially measures sound produced when the laser processing machine100 a processes the workpiece 30 (step S21).

Subsequently, the processing state detecting device 1 a analyzes eachmeasured sound (step S22). In this step S22, each AD conversion unit 12first converts the measurement signal outputted from the correspondingsound collecting unit 11 on a front stage thereof into a digital signal,and the installation position evaluating unit 13 a analyzes the digitalmeasurement signal. Specifically, the installation position evaluatingunit 13 a obtains processing sound and noise components other than theprocessing sound included in each of the measurement signals.

Subsequently, the processing state detecting device 1 a determines datato be used, that is, a measurement signal to be used by the processingstate detecting unit 15 in the process of detecting the processing stateof the workpiece 30 (step S23). In this step S23, the installationposition evaluating unit 13 a calculates the SNR of each of themeasurement signals inputted from the AD conversion units 12, anddetermines a measurement signal with the best SNR to be a measurementsignal to be used in the process of detecting the processing state. Theinstallation position evaluating unit 13 a notifies the data selectingunit 19 of the determined measurement signal. The data selecting unit 19selects and outputs the measurement signal of which the data selectingunit 19 is notified by the installation position evaluating unit 13 afrom among the measurement signals inputted from the AD conversion units12.

Note that the installation position evaluating unit 13 a may hold areference value for the SNR of a measurement signal that can be used bythe processing state detecting unit 15 for the process of detecting theprocessing state of the workpiece 30, and when none of the SNRs of themeasurement signals inputted from the AD conversion units 12 satisfiesthe reference value, the installation position evaluating unit 13 a mayinform the user of such a situation to request the user to change theinstallation position of the sound collecting unit or units 11 b.

As described above, the processing state detecting device 1 a accordingto the second embodiment includes a plurality of sound collecting units11, and is configured to use a measurement signal with the best qualityamong the measurement signals outputted from the sound collecting units11 to detect the processing state of the workpiece 30. This can omit theprocess for the user to correct the installation position of the soundcollecting unit 11 that collects sound to be used in the process ofdetecting the processing state, thereby making it possible to reduce theworkload of the user and the time cost.

Third Embodiment

FIG. 8 is a diagram illustrating an example of a configuration of aprocessing state detecting device 1 b according to a third embodiment.The processing state detecting device 1 b has a configuration obtainedby changing the installation position evaluating unit 13 a of theprocessing state detecting device 1 a described in the second embodimentto an installation position evaluating unit 13 b and replacing the dataselecting unit 19 by a beam forming unit 20. In the present embodiment,the installation position evaluating unit 13 b and the beam forming unit20 that are components differing from those of the processing statedetecting device 1 a according to the second embodiment will bedescribed, and the description of the other components will be omitted.Note that a laser processing machine including the processing statedetecting device 1 b according to the third embodiment has aconfiguration similar to that of the laser processing machine accordingto the second embodiment. The laser processing machine according to thethird embodiment thus has a configuration obtained by replacing theprocessing state detecting device 1 a of the laser processing machine100 a illustrated in FIG. 5 by the processing state detecting device 1 billustrated in FIG. 8.

In the processing state detecting device 1 b, measurement signalsoutputted by the AD conversion units 12 are inputted to the installationposition evaluating unit 13 b and the beam forming unit 20.

The installation position evaluating unit 13 b determines whether or noteach of the measurement signals inputted from the AD conversion units 12satisfies a predetermined reference quality. The installation positionevaluating unit 13 b obtains the SNR of each of the measurement signals,and determines whether the SNR satisfies a predetermined referencevalue, for example. The installation position evaluating unit 13 bnotifies the beam forming unit 20 of the result of determination.

The beam forming unit 20 performs beam forming with use of a measurementsignal determined to satisfy the predetermined reference quality by theinstallation position evaluating unit 13 b among the measurement signalsinputted from the AD conversion units 12. Specifically, the beam formingunit 20 performs beam forming with use of the measurement signalsatisfying the reference quality to generate a measurement signal inwhich sound coming from a processing point of the laser processing isenhanced. Because the beam forming performed by the beam forming unit 20is in accordance with procedures of typical beam forming that has beenused conventionally, the explanation thereof will not be provided. Thebeam forming unit 20 outputs a signal generated by beam forming to theprocessing state detecting unit 15.

As described above, the processing state detecting device 1 b accordingto the third embodiment includes a plurality of sound collecting units11, and performs beam forming with use of a measurement signal thatsatisfies a reference quality among the measurement signals outputtedfrom the sound collecting units 11 to generate a signal to be used inthe process of detecting the processing state. As a result, in a casewhere a noise source such as another laser processing machine is presentaround a laser processing machine whose processing state is to bedetected, the influence of noise caused by the noise source can bereduced. This enables the processing state to be detected with higheraccuracy.

Next, a hardware configuration of the processing state detecting devices1, 1 a, and 1 b described above in the embodiments will be described.FIG. 9 is a diagram illustrating an example of a configuration ofhardware for implementing the processing state detecting devicesaccording to the first to third embodiments.

The processing state detecting devices 1, 1 a, and 1 b can beimplemented by hardware parts illustrated in FIG. 9, that is,specifically, a processor 101, a memory 102, an interface circuit 103, adisplay device 104, and an acoustic sensor 105.

The processor 101 is a central processing unit (CPU; also referred to asa central processing device, a processing device, a computing device, amicroprocessor, a microcomputer, or a digital signal processor (DSP)), asystem large scale integration (LSI), or the like. In addition, thememory 102 is a random access memory (RAM), a read only memory (ROM), aflash memory, an erasable programmable ROM (EPROM), an electricallyerasable programmable ROM (EEPROM) (registered trademark) or the like.The interface circuit 103 is a circuit for sending data to and receivingdata from a device external to the processing state detecting devices 1,1 a, and 1 b. The display device 104 is a liquid crystal monitor, adisplay, or the like. The acoustic sensor 105 is a microphone or thelike.

For implementing the processing state detecting device 1, the ADconversion unit 12, the installation position evaluating unit 13, theevaluation result informing unit 14, the processing state detecting unit15, the processing state informing unit 16, the data acquisition unit17, and the learning unit 18 of the processing state detecting device 1are implemented by the processor 101 and the memory 102. Specifically,the AD conversion unit 12, the installation position evaluating unit 13,the evaluation result informing unit 14, the processing state detectingunit 15, the processing state informing unit 16, the data acquisitionunit 17, and the learning unit 18 are implemented by causing the memory102 to store programs for realizing operations of these units andcausing the processor 101 to read and execute the programs stored in thememory 102. In addition, the sound collecting unit 11 of the processingstate detecting device 1 is implemented by the acoustic sensor 105.

Note that the interface circuit 103 illustrated in FIG. 9 is used whenthe data acquisition unit 17 acquires the learning data described above.The display device 104 is used when the evaluation result informing unit14 provides information on an evaluation result and when the processingstate informing unit 16 provides information on a result of detection ofa processing state.

While an example for implementation of the processing state detectingdevice 1 has been described, the processing state detecting devices 1 aand 1 b are implemented in a similar manner.

The configurations presented in the embodiments above are examples ofcontents of the present invention, and can each be combined with otherpublicly known techniques and partly omitted and/or modified withoutdeparting from the scope of the present invention.

REFERENCE SIGNS LIST

1, 1 a, 1 b processing state detecting device; 10, 10 a determinationprocessing unit; 11, 11 ₁, 11 ₂, 11 ₃ sound collecting unit; 12, 12 ₁,12 ₂, 12 ₃ AD conversion unit; 13, 13 a, 13 b installation positionevaluating unit; 14 evaluation result informing unit; 15 processingstate detecting unit; 16 processing state informing unit; 17 dataacquisition unit; 18 learning unit; 19 data selecting unit; 20 beamforming unit; 21 processing machine control unit; 22 processing head; 23nozzle; 30 workpiece; 40 machine learning device; 100, 100 a laserprocessing machine.

1. A processing state detecting device for detecting a processing stateof a workpiece processed by laser processing, the processing statedetecting device comprising: a sound collecting unit including a sensorand configured to measure sound while the workpiece is being processedby laser processing; an installation position evaluating circuit todetermine whether an installation position of the sound collecting unitneeds to be changed, on the basis of the sound measured by the soundcollecting unit; and an evaluation result informing circuit to provideinformation on a result of evaluation of the installation positionevaluating circuit.
 2. The processing state detecting device accordingto claim 1, wherein the sound collecting unit is provided to aprocessing head for irradiating the workpiece with laser light.
 3. Theprocessing state detecting device according to claim 1, wherein when asignal-to-noise ratio of the sound is higher than a predetermined firstthreshold, the installation position evaluating circuit generates anevaluation result indicating that the installation position of the soundcollecting unit need not be changed.
 4. The processing state detectingdevice according to claim 1, wherein when a signal-to-noise ratio of thesound is equal to or lower than a predetermined first threshold, theinstallation position evaluating circuit checks an intensity ofprocessing sound that is a sound component produced by laser processingof the workpiece among components contained in the sound, and when theintensity of the processing sound is lower than a predetermined secondthreshold, the installation position evaluating circuit generates anevaluation result indicating that the sound collecting unit needs to becloser to the workpiece.
 5. The processing state detecting deviceaccording to claim 1, wherein when a signal-to-noise ratio of the soundis equal to or lower than a predetermined first threshold, theinstallation position evaluating circuit checks an intensity of noisethat is components other than a sound component produced by laserprocessing of the workpiece among components contained in the sound, andwhen the intensity of the noise is higher than a predetermined thirdthreshold, the installation position evaluating circuit generates anevaluation result indicating that the sound collecting unit needs to bemoved away from the workpiece.
 6. The processing state detecting deviceaccording to claim 1, comprising: a plurality of sound collecting unitseach being equivalent to the sound collecting unit, wherein theinstallation position evaluating circuit determines a measurement signalwith a best signal-to-noise ratio among measurement signals representingsounds measured by the sound collecting units, respectively, to be ameasurement signal to be used in a process of detecting the processingstate.
 7. The processing state detecting device according to claim 6,further comprising: a processing state detecting circuit to hold alearning model generated through machine learning performed using soundproduced in laser processing of the workpiece and a result of the laserprocessing of the workpiece, and detect the processing state with use ofthe measurement signal determined by the installation positionevaluating circuit and the learning model.
 8. The processing statedetecting device according to claim 1, comprising: a plurality of soundcollecting units which are each equivalent to the sound collecting unit,wherein the installation position evaluating circuit determines ameasurement signal with a signal-to-noise ratio satisfying a referenceamong measurement signals representing sounds measured by the soundcollecting units, respectively, to be a measurement signal to be used ina process of detecting the processing state, and the processing statedetecting device performs beam forming using the measurement signal withthe signal-to-noise ratio satisfying the reference to generate a signalto be used in the process of detecting the processing state.
 9. Theprocessing state detecting device according to claim 8, furthercomprising: a processing state detecting circuit to hold a learningmodel generated through machine learning performed using sound producedin laser processing of the workpiece and a result of the laserprocessing of the workpiece, and detect the processing state with use ofthe signal generated by the beam forming and the learning model.
 10. Theprocessing state detecting device according to claim 1, wherein thesound collecting unit is installed inside a processing head.
 11. A laserprocessing machine comprising the processing state detecting deviceaccording to claim
 1. 12. A machine learning device for generating alearning model to be used in detecting a processing state of a workpieceby a processing state detecting device including a sound collecting unithaving a sensor and configured to measure sound while the workpiece isprocessed by laser processing, an installation position evaluatingcircuit to determine whether an installation position of the soundcollecting unit needs to be changed, on the basis of the sound measuredby the sound collecting unit, and an evaluation result informing circuitto provide information on a result of evaluation of the installationposition evaluating circuit, the machine learning device comprising: adata acquisition circuit to acquire measured sound data and a processingresult of the workpiece, the measured sound data being obtained byconverting sound measured while a laser processing machine whoseprocessing state is to be detected by the processing state detectingdevice performs laser processing on the workpiece into data; and alearning circuit to generate the learning model on the basis of themeasured sound data and the processing result.